Investigations into the source of the infection that was confirmed in chickens on a smallholding at Llanfihangel Glyn Myfyr continue, but 245 possible human contacts are now outside the seven day incubation period to develop the disease.
Marion Lyons, lead consultant in communicable disease control for the NPHS, said the contacts were no longer considered to be at risk.
Seventeen people with mild flu-like symptoms or conjunctivitis are still being monitored after being treated with Tamiflu, but none are seriously ill.
Dr Lyons said a report into the outbreak would be published and lessons learned, including scientific information to add to the body of knowledge about bird flu and practical lessons for handling other outbreaks and for the management of a flu pandemic.
Read the FWi special report on avian flu.